media: venus: hfi_cmds: Fix conceal color property

The conceal color property used for Venus v4 and v6 has the same
payload structure. But currently v4 follow down to payload
structure for v1. Correct this by moving set_property to v4.

Fixes: 4ef6039f ("media: venus: vdec: Add support for conceal control")
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>